STM and DFT study on formation and characterization of Ba-incorporated phases on a Ge(001) surface

Abstract

We characterize the incorporation of Ba adatoms into the Ge(001) surface, resulting in the formation of one-dimensional structures with an internal 2 × 3 periodicity, after the deposition of Ba atoms at 970 K or at room temperature followed by a 770 K anneal. Scanning tunneling microscopy (STM) data were compared with theoretically simulated STM images generated by density functional theory electronic structure calculations. Excellent agreement between experiment and simulation was found when using an adopted structural model that assumes partial removal of the surface Ge dimers in the [1-10] surface direction and subsequent addition of a single Ba atom to the substrate second layer. Structural assignments for a number of defects observed within regions of the 2 × 3 reconstruction were also obtained.

Reversible c(4x4)↔(1x2) phase transition on the Ba/Ge(100) surface controlled by oxygen adsorption and desorption

“…In previous studies of adsorbed barium layers on the Ge(100), several reconstructions already have been reported forming in the region of submonolayer coatings, namely: in (2 × 3), (4 × 3) and c(2 × 6) structures with 1/6 ML coating, in (9 × 1) in the coating interval of 1/4−1/2 ML and in (6 × 1) with 1 ML coating [9][10][11]. The atomic structure of these adsorbed phases have been studied by scanning tunneling microscopy (STM) and quantumchemical calculations based on the density functional theory.…”

Обратимый фазовый переход c(4x4)↔(1x2) на поверхности Ba/Ge(100), управляемый адсорбцией и десорбцией кислорода

“…В предыдущих исследованиях, посвященных адсорбированным слоям бария на Ge(100), уже были получены сведения о ряде реконструкций, формирующихся в области субмонослойных покрытий, а именно: структурах (2 × 3), (4 × 3) и c(2 × 6) при покрытии 1/6 ML, (9 × 1) в интервале покрытий 1/4−1/2 ML, а также (6 × 1) при 1 ML [9][10][11]. Атомное строение этих адсорбционных фаз было изучено с помощью сканирующей туннельной микроскопии (СТМ) и квантово-химических расчетов на основе теории функционала плотности.…”